We conjecture a new ordinary differential equation exactly isospectral to the radial component of the homogeneous Teukolsky equation. Surprisingly our equation looks much simpler than Teukolsky's one. We find this novel relation by a hidden symmetry implied from a four-dimensional N = 2 supersymmetric quantum chromodynamics. Our proposal is powerful both in analytical and in numerical studies. As an application, we derive high-order perturbative series of quasinormal mode frequencies in the slowly rotating limit.